Michael Kopech’s excellent 2015 season took a turn for the worse Thursday.

The Boston Red Sox pitching prospect was suspended 50 games after testing positive for Oxilofrine, a stimulant in violation of the Minor League Drug Prevention and Treatment Program. Kopech, who has spent the entire season with Single-A Salem, apologized in a statement, though the 19-year-old right-hander also denied knowingly taking the banned substance.

Kopech issued the following statement to MiLB.com:

“I would like to start by apologizing to all of baseball, baseball fans, and specifically the Red Sox and Red Sox fan base. I respect the game as much, if not more than, anyone else.

“With that being said, I never have and never will intentionally cheat the game that has been so great to me. I haven’t bought any supplements that aren’t NSF certified for sport. Therefore, I know I have not bought a supplement containing this drug. I have never heard of Oxilofrine, honestly. Apparently, it is a drug that many people use for weight loss. I have been trying to gain weight since I signed with the Red Sox. I do understand this is also a stimulant. This drug would have no positive outcome for me and that’s why I chose to appeal.

“I realized I didn’t have much evidence to prove that I’m innocent, but I didn’t have any understanding of how I could have failed a test. I respect the system and understand why they have to be so careful with the testing. I also understand why that means my suspension couldn’t have been overturned without proper evidence. I have 50 games to get to work and better myself and as a ball player. Next season I’ll be better than ever. Drug free.”

Kopech, a first-round pick (No. 33 overall) in 2014, went 4-5 with a 2.63 ERA in 16 games (15 starts) with Salem this season. He’s the Red Sox’s No. 10 prospect, according to MLB.com.

Thumbnail photo via Twitter/@vincelara